A train carrying a wide-variety of toxic chemicals derailed in East Palestine, Ohio on February 3.
Some of those chemicals have since been released into the air or soil, as residents worry about the long-term health effects.
Among the chemicals released from the derailment are:
Vinyl chloride — train operator Norfolk Southern has said that 10 cars were burning vinyl chloride, a known carcinogen. It is a highly-volatile colorless gas used to create polyvinyl chloride, a plastic used in piping, cables, bottles and credit cards.
Symptoms of vinyl chloride exposure includes drowsiness, headaches and dizziness. More long-term effects may include cancer and liver damage.
Hydrogen chloride — In trying to mitigate the effects of vinyl chloride, officials conducted a controlled explosion of the train cars, releasing hydrogen chloride.
The chemical is irritating and corrosive to any tissue it gets in contact with, the Centers for Disease Control and Prevention warns.
Brief exposure can cause throat irritation, but exposure at higher levels can result in rapid breathing, narrowing of the bronchioles, blue coloring of the skin, accumulation of fluid in the lungs and even death.
Phosgene — a chemical that was also released in the controlled explosion.
Like hydrogen chloride, phosgene is an irritant to the skin, eyes and respiratory tract.
Common initial symptoms include mild irritation of the eyes and throat, with some coughing choking, nausea, occasional vomiting, headache and a feeling of tightness in the chest.
Phosgene poisoning may also cause respiratory and cardiovascular failure, low blood pressure and an accumulation of fluid in the lungs.
Ethylhexyl acrylate — a chemical that was carried on the train
It is a known carcinogen, that can cause burning and irritation of the skin and eyes. Inhalation of the substance can also irritate the nose and throat, causing shortness of breath and coughing.
Isobutylene was also being transported on the train.
Inhalation of isobutylene can cause dizziness and drowsiness
Ethylene glycol mobobutyl was another substance being transported to Pennsylvania.
It can cause irritation in the eyes, skin, nose and threat, as well as hematuria (or blood in the urine), nervous system depression, headache and vomiting.